Prints made from photographs of the night sky taken with telescopes from the Royal Observatory Greenwich in England between 1892 and 1909 as part of the Carte du Ciel celestial mapping project. The photographs are centered horizontally at declinations of +65, +66, +67, +68, +69, +70, +71, +72, +73, +74, +75, +76, +77, +78, +79, +80, +81, +82, +83, +84, +85, +86, +87, +88, +89 and +90, and vertically at right ascensions (RA) ranging from 0 hours, 0 minutes through 23 hours, 51 minutes. The distance between vertical centers of the prints differs by declination: from +65 to +66 declination, the RA distance is 18 minutes, from +67 to +70 declination the RA distance is 20 minutes, from +71 to +74 declination the RA distance is 24 minutes, from +75 to +78 declination the RA distance is 30 minutes, from +79 to +82 declination the RA distance is 40 minutes, from +83 to +85 declination the RA distance is one hour, from +86 to +87 declination the RA distance is 1.5 hours, at +88 declination the RA distance is two hours, at +89 declination the RA distance is three hours, and at +90 declination ??
